The major number in a special file entry identifies the device driver. Each driver in a Linux or Unix kernel has a number. The major number just selects the driver, e.g. if a serial port driver or a hard disk driver should be associated with the name in the file system

Minor number

The minor number in a special file entry is interpreted individually by a particular device driver. For example a serial driver might use it to compute the I/O address of a UART, or a hard disk driver might use it to address a particular disk on the periphery bus

First some background. 'mtd' stands for memory technology device. Traditionally Unix (and Linux) just has two device types

Block special files

Character special files

The interfaces of these special files is and was primarily geared at communicating with devices like hard disks, tapes, or terminals. Flash memory, or other 'memory technology' doesn't match to well to the classic device interfaces. For example, writing to a flash device should usually be more controlled to avoid excessive wear and tear of the memory (flash memory allows just a limited number of re-writes). So a particular mtd interface was created in the kernel to support these devices better. In addition, for backward-compatibility with non-mtd-aware software and tools (most are not mtd-aware) the mtd interface was mapped back to the classic block and character special device interfaces. The LinkStation firmware contains the necessary mtd device driver and matching file entries under /dev.

The following information only applies to firmwares 1.41 and newer. Firmwares prior to 1.41 function the same as powerpc-hdhlan firmwares.

You can change the boot status by using write_ng and write_ok. To change the boot status to normal:

write_ok

To change the boot status to EM mode:

write_ng

WARNING!

There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. Be very careful when changing the boot status to EM mode! You can easily lock yourself out of the LinkStation and possibly brick the unit. Always change the boot status to normal before rebooting.

/dev/mtd3

Contents of conf_save.tar.gz:

???

You can read and write conf_save.tar.gz to and from /dev/mtd3 by using /usr/bin/as_flash: